Squash bugs

Squash bugs are a pest of squash. At this time of year, the adults are tucked away safely on the edges of gardens and fields in a state of diapause. Their reproductive systems have halted development; their metabolism has slowed to a low level. They are snug under the snow waiting for conditions to improve.

In the late spring, the adults will break diapause, metabolism and respiration will increase and the adults will seek squash plants to lay their eggs. Like many of the true bugs, squash bugs feed on a variety of plants. If given no choice, they will feed on plants in families other than the squash family (Cucurbitaceae) including ornamental plants such as coleus. It is interesting that squash bug will briefly feed on a wide variety of plants, but it can only develop and reproduce on squash. I have managed to rear squash bug on cucumber plants for over 6 weeks. They feed enough to survive. However, they never reproduce and their reproductive organs never mature. Mating requires squash.

One might think that an insect so dependent on squash for reproduction would have evolved the ability to detect squash plants from afar, either through vision or olfaction. However, squash bugs seem not to use any long range cues. Finding a host plant seems to be a random process. This is where feeding on plants that are not hosts is important.

Squash bug adults leaving their overwintering quarters will encounter many plants. If hungry or thirsty, they will stop to feed. They can get water, possibly sugar and other nutrients from these plants. However, these plants must be lacking some substance necessary for reproduction. The squash bug will feed briefly on non-host plants and move on. It will feed on the next plant and the next until eventually, it reaches a squash plant (or dies). When it reaches a squash plant, it will feed for longer periods and feed repeatedly.

This seems to be an inefficient process, but it works. Every year I have squash bugs on my squash plants. When they leave their overwintering quarters, squash bugs have no idea where they are going. However, once they arrive on my squash plants, they know where they are staying.

Squash bugs, Anasa tristis