JULY
1989

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

7-27-89

Arsenic And Old Lacewings

Lacewings are the "arsenic and old lace" of the insect world. These insects are small—less than a half-inch in length. To us, they appear quite fragile, soft-bodied with four clear, membranous wings. The many cross-veins in their wings create an image, well, of lace. That is the basis for their name. But to their prey, lacewings are as deadly as arsenic.

Lacewings, which are classified in the insect order Neuroptera, are considered ancient insects. Bearing resemblance to miniature prehistoric monsters, most are greenish or brown with golden-colored eyes. Their long antennae and fearsome chewing mouthpart~ suggest that lacewings are not part of the gentle, nectar-nipping set of the insect upper crust. Quite the opposite.

Both lacewing adults and larvae are random predators. They roam plants with the fervor of hungry diners scanning a menu as they search for insects. Aphids are a favorite food. Lacewing larvae have a pair of sickle-shaped jaws that are piercing-sucking tubes. When a prowling larva, appropriately called an aphislion, encounters an aphid, the end is swift. The victim is impaled on the lacewing's sharp jaws while fluids are sucked from the victim's body like soda through a straw.

Larval lacewings are such dedicated predators that even their brothers and sisters are potential meal~. Among lacewings, the first hatched has an advantage. Newly hatched larvae begin a fervent search for food. Almost anything will do -- even an unhatched lacewing egg. No amount of parental cajoling would likely prevent this ultimate expression of sibling rivalry. So lacewing mothers-to-be place their eggs on a stalk, just out of range of hungry little jaws. Of course, when larvae hatch and descend from the safe hatching perch, they're on their own in the dog-eat-dog world of lacewings and aphids.

Many gardeners have gained a great appreciation for the appetite of lacewings. In fact, lacewings have biological control potential and have even gained commercial status. Gardeners can purchase lacewings to help control the undesirable creatures that show up in their gardens -- at least undesirable creatures of the insect variety. Lacewings are of no help whatsoever when it comes to hungry neighbors who seem to show up at the garden when the work is done and the harvest begins!

 

Writer: Tom Turpin
Editor: Carol McGrew