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About Thrips and Weevils

Updated on September 13, 2014



Thrips are a gregarious lot

There is no such thing as one thrip. The word "thrips" is both singular and plural and, since one thrips is inevitably followed by another, the singular form is rarely used.
Thrips are a gregarious lot. They congregate by the hundreds on flowers and leaves. Without the aid of a hand lens, they resemble tiny dark threads. A closer look reveals their narrow, fringed wings folded flat on the back and cone-shaped mouthparts. Extremely active insects, they leap and fly away when disturbed. If not in any particular hurry, they may crawl with the abdomen lifted and perhaps curved over their backs.

Ponticulothrips diospyrosi


Some eat other Thrips

Most thrips are plant-eaters. To feed, they scrape the epidermal layer of the host plant, then suck the cell sap as it flows into the wound. Some species may burrow between the upper and lower leaf surfaces to feed. Blossoms become streaked with brown and wither prematurely. Injured leaves are twisted or discolored and scarred. The fruit of host plants is often pitted.
A few species are beneficial predators of mites, small insects, and other thrips. Most of these can be distinguished by their banded or mottled wings.

Four Instars

Metamorphosis in this order is incomplete with the nymph passing through four instars. Eggs are inserted in leaves and stems. One to two weeks later, nymphs emerge and begin to feed. During the first three stages, the pale wingless young feed actively but in the final period, they are entirely quiescent. Some species form a cocoon on the ground or on the host plant at this time.
Many generations may occur each year, but largest populations are present from late spring to midsummer. Yet, even during this period, thrips seldom cause serious damage to their host. Their worst effect is russeting or, in the case of citrus thrips, early blossom drop.

A Novel Approach to Controlling Thrips

Weevil - Rhinotia haemoptera



Weevils are beetles whose mouthparts are attached to the end of a beak or snout. Those with a particularly long or pronounced and curved snout are sometimes called curculios. Garden species are mostly small, dull colored, and hard shelled.
Adults are potential plant pests, but usually larvae cause the most serious injury. They feed on fruits, nuts, and plant roots. Eggs are laid in or on the plant where larval feeding will occur. Larvae feed and pupate within the plant, emerging later to lay eggs. There may be several generations per year, depending upon the species.

Botany Bay Weevil


Weevil control tips

A few weevils are bound to turn up in most fruit and root crops. This is to be expected and does not mean that the entire crop has "failed." But, if weevil populations do get out of hand, you may find it necessary to shorten their life cycle. Pick up dropped fruit and bury it very deep. Eliminate the insects' hibernating spots in garden trash and the upper inches of the soil. Since weevils tend to drop from trees and bushes when disturbed, you can collect them throughout the summer by placing a sheet beneath the infested tree and shaking the branches. If these control measures fail, dust foliage with diatomaceous earth

Bizarre Giraffe-Necked Weevils Fight for a Mate


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