Crawlies with Cri: Chalcid wasp

Chalcid wasp

This week’s crawly is a micro-mini garden superhero! Meet the Genus Microterys chalcid wasp (we’ll call them “micro” for short).
At just over one-sixteenth of an inch (look at a ruler; that is super small!), these nifty wasps may go overlooked despite their beautiful, bold coloration. If you’re really looking, however, they do stand out when meandering around on leaves, especially green leaves.
Aside from their incredible good looks, what makes micros so magnificent? These lovely ladies spell “Capital D” Doom for scale insects.
If you aren’t familiar with scale insects, that’s great, but let’s do a brief overview. There are about 8,000 described species of scale insects, the vast majority of which are considered plant pests.
They are tiny true bugs closely related to aphids and whiteflies. They vary in size and appearance, but they all mature beneath a waxy covering attached to a plant part (leaf or stem). Those coverings look like individual fish or reptile scales – thus the “scale insect” name.
Scale insects cause damage to plants in two ways: 1) They drink the plant’s sap; 2) They exude sticky honeydew which supports the growth of sooty mold, causing more plant damage.
Enter our micro heroine! Micros help eliminate scale insects by parasitizing them. Females use their ovipositors to pierce those waxy shields, then lay their eggs in with the larvae of the scale insects. When the micro wasp eggs hatch, they chow down on the scale larvae.
The waxy shields will remain, protecting the wasp larvae until they hatch, but no damage will be caused to the plant. No sap sucked, and the overall population of scale insects will be culled.
There are 16 species of micros found throughout the United States. They can be found nearly year-round. The two pictured micros were both found on the same day in December. It was an unseasonably warm day, warm enough that the overwintering micro eggs hatched, and the winged adults immediately began looking for some hosts to lay in another round of eggs.
This ability to hatch on any given “warm enough” day is another leg up micros have over their scale prey. While most insects in cool climates can only have one or two broods per year and must overwinter or hibernate from fall to spring, micros can pop up midwinter and put a halt to one more spring batch of scale insects.
But wait, there’s more!
Micros are in the Family Encyrtidae, known as encyrtid (en-SIR-did) wasps. There are 480 species of wasp in their family and every one of them is a pest controlling heroine.
Many of those 480 species specialize in scale and mealy bugs, but not all. The list of crawlies they parasitize reads like a “Most Wanted” poster: beetles, true bugs, white flies, loopers, caterpillars, grasshoppers, flies, leafhoppers, spiders and…wait for it…ticks. Yes, ticks!
Encyrtids deserve a national holiday just for getting rid of ticks.
With over 400 species around, it’s guaranteed you have some in your yard. If you want to keep them there – and you do, it’s free pest control – avoid regular use of synthetic, broad-spectrum pesticides.
Infrequent use of certain narrow-spectrum pesticides is more compatible with some beneficial wasps, but generally the less chemical inputs there are, the greater and more diverse the beneficial insect community will be and the more time and money you’ll save.