Sunday, July 15, 2012

Squash Bugs

The title can be taken several ways and we'll get to both. The first meaning is the name of a common garden pest, the Squash Bug (Anasa tristis), one of a group of insects referred to as "True Bugs" (the Order Hemiptera, if you need that for Biology class). The term "bug" is casually interchanged with "insect," but might be used to refer to a beetle, grasshopper, fly or moth (all of which are actually separate orders and deserve their own names). As a group, True Bugs have a set of folding hind wings used for flight and, when at rest, these are covered by a set of protective forewings that are membranous at the tips and leathery at the base where they attach to the body. The word Hemiptera means "half wing," as in half-membranous.

Adult Squash Bug showing half-membranous wings -- © Dave Spier

True Bugs also have sucking mouth parts, often shaped like a beak at the front of the head, and here's where they become a nuisance. Squash Bugs suck the juices from the leaves of any gourd plant, including squash, cucumber, melon and pumpkin. 

Adult Squash Bugs mating -- © Dave Spier

After mating, the adults glue clusters of bronze-colored eggs to the undersides of leaves and when these hatch, the young nymphs have a ready made food supply. The powder-blue colored nymphs grow through five stages [instars] as they become more and more adult-like and do more and more damage until the plant's leaves wither and dry to a crisp. They will overwinter under the shelter of dead leaves, so one method of control involves cleaning up all plant remnants and burning or disposing in the trash.

Squash Bug eggs on the underside of a leaf -- © Dave Spier

The other method of control that I employ as an organic gardener is to search-and-destroy by squashing all these particular bugs, eggs and nymphs that I find, hence the second meaning of the title. The adults are 5/8-inch long, gray-brown above, pale below and their wide abdomens can be edged with orange or striped with brown. They have heavy-duty "shoulders" giving a hunched-back appearance.

Young nymph -- © Dave Spier

Older nymph emerging -- © Dave Spier

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