Skip to main content









Donation Heart Ribbon

Local Bug Population Booming


Have you noticed a bunch of bugs flying around your porch light lately? We talk to a local entomologist about why the local bug population is booming, and what insect species are buzzing around San Diego right now.

MAUREEN CAVANAUGH (Host): I'm Maureen Cavanaugh, and you're listening to These Days on KPBS. We've had a good mix of rain and warm weather through the late winter and spring, and as it turns out that's a good breeding ground for spring flowers, and it's also great for spring bugs. In fact, some are predicting a bumper crop of bugs into the summer. For the latest on the new residents crawling and flying around your neighborhood, I’d like to welcome my guest. Dr. Michael Wall is curator of entomology and director of the Biodiversity Research Center of the Californias at the San Diego Natural History Museum. And, Dr. Wall, good morning.

DR. MICHAEL WALL (Curator of Entomology, San Diego Natural History Museum): Good morning. How are you?

CAVANAUGH: I’m great. Thank you for coming – well, thank you for speaking with us today.

DR. WALL: It’s my pleasure.

CAVANAUGH: Now has this been a good bug season in San Diego?

DR. WALL: Yeah, absolutely. And you kind of hit the nail right on the head in talking about the distribution of rains and the warm weather. All that’s really good for the plants and – or as entomologists refer to them, it’s good for the bug food. So whatever’s good for the bug food is going to end up being good for the insects so it really is going to be, and already is, a bumper crop.

CAVANAUGH: What kind of insects are we seeing right now, you know, in this early springtime?

DR. WALL: Yeah, well, it depends on what part of the county you’re in on what’s going to be sort of the most predominant things that you’re seeing but, as I mentioned, you know, the – if you’ve got plants then you’re going to have a lot of – what we’re going to see first are going to be a lot of insects that eat plants so people are probably seeing a lot of caterpillars out there, probably the caterpillars are things like Painted Lady Butterflies, maybe – there’s this other moth that’s called the White-lined sphinx moth, and then also various types of what we call Looper moths, which are just kind of indescript (sic) gray moths. But then as the season continues, all these insects that are the plant-eaters are going to start being food for all the insects that are insect-eaters, so we’re going to start seeing things like these predacious beetles that eat caterpillars and various types of wasps that also prey on other types of insects. So that’s sort of the way that it’s probably – that I’m predicting that it’s going to go down.

CAVANAUGH: I’m speaking with Dr. Michael Wall, he’s director of the Biodiversity Research Center of the Californias at the San Diego Natural History Museum. And we’re talking about spring bugs. I’d like to remind our listeners that if they’d like to join the conversation we’d like to hear your bug question. If you’ve got a bug you haven’t seen before or more bugs than usual, give us a call at 1-888-895-5727. Now, Dr. Wall, I read in the paper yesterday that state officials have been releasing sterile male Mediterranean Fruit Flies all over the county to stop the reproduction of wild Med flies. Where do these Med flies come from and why is this effort being made?

DR. WALL: Originally, the Med fly, despite its name, it came from Africa but it has since spread pretty much throughout Mediterranean climates around the world. And it particularly loves citrus but it’s known to eat lots of different types of fruits and vegetables. And the – what they’re doing, as you said, is they’re releasing all of these sterile males which they’ve irradiated so that they can’t reproduce and the idea is, is that by swamping an area with enough sterile males that the females will never become, you know, the females will never become mated by a non-sterile male and be able to lay eggs. And this tactic’s been used pretty successfully in Florida and other areas of the world.

CAVANAUGH: You know, you just finished telling us about moths, I did want to ask you, are there moths – are – they pose any danger to people?

DR. WALL: No. I mean, the – some of these moths that I was talking about, like these Looper moths in particular, are well known by gardeners to come in and eat things in the garden like celery and lettuce and various types of early spring things. So the only way they’re of danger to people is by eating the food that we want to eat in our garden.

CAVANAUGH: And we do have a call. Tom is calling us from Oceanside. Good morning, Tom, and welcome to These Days.

TOM (Caller, Oceanside): Yes, good morning. I wanted to find out, what’s the best way to handle whiteflies?

DR. WALL: Umm-hmm. That is a good question and I assume – are you talking about whiteflies outside? Or on your inside plants?

TOM: It’d be mostly on the outside.

DR. WALL: Probably on something like hibiscus?

TOM: Yes, correct.

DR. WALL: Yeah. Yeah. One of the best ways – I mean, one thing that you can do straight off the bat is go ahead and remove highly infected leaves, I guess. You know, areas where you do have a lot of whiteflies, to go ahead and try to reduce that population down as much as possible. And then there’s various types of insecticidal sprays and soaps and oils that can be effective against whiteflies but it’s one of the harder things to be able to effectively treat.

CAVANAUGH: Well, thank you for the call, Tom. Are there any bugs out about now that might be considered dangerous? That people maybe should look out for?

DR. WALL: The – what I have been getting some phone calls and e-mails about here at the museum is this is the time of year where we’re going to start seeing bees swarm, and I’m talking about European honey bees swarming. And actually, you know, even though it looks intimidating if you look out into your backyard and you see a whole swarm of bees sitting on like a frond of one of your palm trees or one – hanging from a branch in your yard, swarm – when a bee is swarming, it’s actually one of their more kind of docile stages, not that I’m suggesting that you approach it in any sort of way.


DR. WALL: But they’re not considered to be incredibly aggressive at this point, and so if people see these in their backyards, the best thing to do is just kind of leave it alone because what’s happening with the swarm is that one hive has broken up into two hives and half of the hive left the original nest and is looking for a new nest.


DR. WALL: And so they’re not going to nest out in the open, they’re not going to start putting out wax on your palm fronds and out in the open like that. They’re just kind of – it’s a rest stop while they try to find a permanent area to make a home.

CAVANAUGH: Let’s hear from another caller. Mark is calling us from Escondido. Good morning, Mark. Welcome to These Days. Hi, Mark. Are you there? Okay, we’ll just move on.

DR. WALL: Nah, no problem.

CAVANAUGH: I was just going to ask you…

MARK (Caller, Escondido): Hello?


MARK: Yes.

CAVANAUGH: Okay. What’s your question?

MARK: My question is, I’ve got these little (call dropped)

CAVANAUGH: Ah. Mark is not having a good day.

DR. WALL: No, that’s not…

CAVANAUGH: I wanted to ask you about when we talk about bugs that might be considered dangerous, what about some spiders?

DR. WALL: Yeah, right now, this time of the year, mostly what’s happening with spiders is that the babies are starting to hatch from last year. And so we don’t tend to see a lot of big, giant spiders this time of year, not that you don’t. I mean, there certainly are some big ones that are left over from last year. But the two dangerous spiders here in San Diego County are black widow spiders and the brown widow spiders and they’re both very closely related to one another, look very similar, both have that kind of reddish-orange hourglass on the underside of their bodies. They’re going to start becoming bigger later in the year but what people are probably going to encounter at this time of the year is, you know, as we go outside and we start using our outside areas more and stuff like that, you’re probably going to find the webbing from and some of the egg masses that were from last year. And the black – or, excuse me, the brown widows, in particular, have the eggs are very characteristic. They look like kind of those World War II era sea mines, you know, those little balls that have the spikes all over them.

CAVANAUGH: Umm-hmm. Yes.

DR. WALL: And so when people are going out into their patio furniture and, you know, enjoying the outside space a little bit more, take a look underneath your cushions and stuff like that and look out for these little World War II era sea mines and just – you can crush them or do whatever you want to to get rid of them.

CAVANAUGH: Well, thank – that’s – that’s great. That’s great advice to just look over your patio furniture and make sure you’re not going to be stung by anything.

DR. WALL: Sure.

CAVANAUGH: David is calling us from Oceanside. Good morning, David. Welcome to These Days.

DAVID (Caller, Oceanside): Hi, Maureen. Your screener said it right. We gotta get this answered once and for all.

CAVANAUGH: What is this?

DAVID: These things that look like giant mosquitoes which I know are not giant mosquitoes…

DR. WALL: Oh, okay.

DAVID: …that my 11-year-old goes running in fear and her friends go running from them. What are those?

DR. WALL: Right. Those are called mosquito hawks but that’s actually a misnamer (sic) as well because they’re – they aren’t predators of mosquitoes either. They’re these things that are also called crane flies and they do look like giant mosquitoes but they’re very, very innocent. Their larvae just feed on kind of dead and – plant matter so in your compost and stuff like that. And then the adults just feed on nectar of flowers. So they’re very innocent but they are the – they’re what the urban legends of summer camp are made of, of the three-foot-long mosquitoes and stuff like that.

CAVANAUGH: Very good. Thanks for the question, David. You know, These Days producer Hank Crook has noticed a bug in his yard that looks like a big yellow grasshopper and it buzzes very loudly and he actually got a clip of the way it sounds, so let’s hear the – that Hank Crook bug.

(audio of unidentified insect noise)

CAVANAUGH: Now, do you have any idea what that is, Dr. Wall?

DR. WALL: I think that’s probably some sort of katydid or possibly a cicada. But if it looks like a big yellow grasshopper, then it’s most likely a katydid of some sort.

CAVANAUGH: Now, and so if it is a cicada, though, it would have to be cicada season, wouldn’t it?

DR. WALL: Yeah, and cicadas actually here in Southern California, unlike, you know, the east coast where you…


DR. WALL: …hear about these big periodical cicadas coming out every 13 years in these huge droves and stuff like that, here in Southern California, most of our cicadas are – they just – they don’t come out in those huge droves and they’re not quite – they come in different seasons so there actually are a few cicadas that are out right now.


DR. WALL: We will get more as the summer goes on but there are some species that are out right now.

CAVANAUGH: Let’s get another call.

DR. WALL: Okay.

CAVANAUGH: Dave is calling us from Pacific Beach. Good morning, Dave. Welcome to These Days.

DAVE (Caller, Pacific Beach): Good morning. Thanks for taking my call. I actually had a question but first I wanted to respond to an earlier caller about whiteflies on hibiscus. I had a really bad infestation and, in fact, on all of – I have several hibiscus plants in my yard and they all had really bad infestations and the systemic plant food that you can get, you know, even at Home Depot, I think it’s Bayer, any nursery can provide you with that. I don’t like systemics because you’re not supposed to use them near anything you’re going to eat, you know, you’re putting poison into the ground but it did work very, very effectively.

CAVANAUGH: Okay, well, thank you.

DAVE: And I understand that worm castings are a good food for plants to ward off whiteflies. My question for your guest is are there any insects that eat termites?

CAVANAUGH: Oh, great. Great. Yeah, we’d love to hear that, Dr. Wall.

DR. WALL: Yeah, I mean, certainly. I mean, when you look at a termite it just – it looks so – I mean, we might look at them and say, ooh, gross, but they are pretty defenseless looking creatures. You know, they’re just kind of big balls of goo with a little head capsule. And there are plenty of things that eat termites but you’re probably more specifically talking about things that are going to be eating the termites in your house and, you know, possibly using them in some sort of control for the termites in your house. And there, ehh, you know, that – I’ve never heard of anyone doing anything like that with great success because most of the things that we have around here that actually eat termites are just generalist predators. They’ll kind of eat a termite when they encounter them. They might eat the, you know, the male and females they take flight – male and female termites take flight during the year and so birds would eat those and all that sort of stuff but in terms of actually being able to control them, ehh, there hasn’t been a lot of success with that.

CAVANAUGH: You know, I was recently talking to a veterinarian and I was told that this might be a very big year for fleas and ticks. Do you think so as well?

DR. WALL: I’m not sure about fleas. To me honest with you, I don’t really know the – you know, what controls their population explosions that well. Ticks, you know, whether or not it’s going to be a good season for ticks really kind of has to do with how the season has been for the things that ticks normally feed on, so rodents, coyotes and stuff like that out in our canyons. And so it might be a big year for ticks but it might be a big year for ticks only because it’s such a nice season for wildflowers that more people are outside walking their dogs and getting out there and actually increasing…


DR. WALL: …their chances for encounter.

CAVANAUGH: I see. I see what you’re saying.

DR. WALL: I don’t know. I’m guessing.

CAVANAUGH: Rinata is calling us from La Mesa. Good morning, and welcome to These Days.

RINATA (Caller, La Mesa): Good morning. Hello?


RINATA: Hi. I have a question about something that has been plaguing my rosemary plants for years. Every spring the plants develop these white spit-like blobs scattered around the branches.

DR. WALL: Umm-hmm.

RINATA: And I’m wondering if, you know, what this is and also if it may be related to another problem I seem to have at the same time, which is these teeny white – not teeny but small white moths.

DR. WALL: Hmm.

CAVANAUGH: Interesting. Thank you.

DR. WALL: Yeah, I don’t think those are related because what’s causing the little spit blobs is something that’s appropriately called a spittle bug. And it’s kind of – probably the thing that most people would be familiar with is that it’s related to an aphid and what happens is that these little insects, they stick their mouth parts – their mouth parts are kind of like a straw and they stick it into the plant and they start sucking out the juice of the plant. Well, the juice doesn’t have enough nutrients in it for – to, you know, really help the insect grow unless it processes a lot of that plant juice and so all of the water comes out the other end. It bubbles it up and it actually uses that little – it lives inside of that bubble, you know, spit-looking thing and it also kind of doubles to help his defense because what sort of insect wants to like, you know, cruise through a bunch of spit to eat, you know, eat the insect that’s inside of it. And the little white moths, I’m afraid I can’t help you with that. I mean, there’s lots of little white moths out there and I’m not sure specifically which one that might be causing a problem for you.

CAVANAUGH: You know, I – Dr. Wall, I know that you love bugs and yet you’re giving good advice as to how to – people can control the number of bugs in their area. I wonder if you don’t feel conflicted about that?

DR. WALL: Well, I, you know, I get asked for advice a lot of times on controlling insects and stuff like that and I – and, you know, I try to give the best advice I can but, you know, I often finish off with saying like that’s not the type of entomology I do, you know.

CAVANAUGH: Yes. Right, right.

DR. WALL: You know, we’re – here at the San Diego Natural History Museum, are most interested in educating people about the, you know, our local biodiversity and certainly insects make up a large part of that diversity and, by and large, most insects that are out there – I mean, not even by and large. If – Statistically speaking, most insects out there aren’t hurting humans in any shape, fashion or form whatever. If anything, they’re benefiting the world by pollinating our plants and decomposing plant matter and all that sort of stuff. So I understand that, you know, I have – I have Argentine ants coming into my house and I have, you know, things eating the stuff in my garden. I sympathize.

CAVANAUGH: Well, Dr. Michael Wall, thanks so much for speaking with us today. I really appreciate it.

DR. WALL: My pleasure.

CAVANAUGH: I’ve been speaking with Dr. Michael Wall. He’s curator of entomology and director of the Biodiversity Research Center of the Californias at the San Diego Natural History Museum. I want to let everyone know that they can join us next Monday on These Days for tips on how to control the bugs in your backyard. We’ll be devoting a whole hour to spring gardening in the ten o’clock hour of These Days. That’s coming up next Monday. And if you’d like to comment about what you’ve heard on These Days, go to Stay with us for hour two coming up in just a few minutes here on KPBS.

Want more KPBS news?
Find us on Twitter and Facebook, or subscribe to our newsletters.

To view PDF documents, Download Acrobat Reader.