IPM Control Strategies for Caterpillars – Trichogramma + BT NOW

In the world of biological crop protection, pest control materials based on fungi and bacterium are often used to target specific insect pests, such as caterpillars. Caterpillars are significant pests in a wide variety of crops and can have a major impact on farms. Controlling caterpillars is vital to protecting yields and crop quality, which helps many farmers sustain their businesses.

Scouting (regularly walking crop fields and inspecting for the presence of pests or pest damage) is an essential part of good pest management practices. The goals of scouting are to catch caterpillars early in an infestation and early in their life cycle – this will give the grower the best chance to control the pest and minimize damage to the crop. There are different treatment thresholds (numbers of caterpillars per given area) for different crops; these are usually published in regional crop production guides. 

Caterpillars are easier to control when they are small – the bigger a caterpillar gets, the more destructive, and harder to kill, it will be.  Sticky traps baited with species-specific pheromones and placed in and around crop fields can alert growers to the presence of adult moths. This can help growers determine when to begin scouting.  Once moths have been observed, we suggest at least a weekly scouting pass through crops known to be a host of caterpillar pests.

Caterpillars tend to leave obvious signs of their presence in the form of chewed and skeletonized leaves, damaged stems, and frass (droppings). Small holes in leaves caused by newly hatched caterpillars can quickly escalate into major damage or crop loss.

Fortunately, when caterpillars are detected early they can usually be managed successfully. Integrated Pest Management (IPM) practices involve using multiple, complementary approaches to control pest outbreaks.  For example, BT NOW® and Trichogramma spp. are two naturally occurring, biological organisms that specifically target caterpillars.

Trichogramma ostriniae
Peggy Greb, USDA Agricultural Research Service, Bugwood.org

Trichogramma are minute wasps (1/50th of an inch) that parasitize the eggs of over 200 species of moths and caterpillars. Releasing Trichogramma when adult moths first begin laying eggs is ideal. 

BT NOW, which contains a novel strain of the bacteria Bacillus thuringiensis (Bt), effectively targets hatched caterpillars that the Trichogramma may have missed. BT NOW should be applied 3–7 days after moths first lay eggs to target newly emerging larvae. 

A well-timed combination of Trichogramma release and a BT NOW application can achieve excellent control of caterpillars without leaving any harmful residues or disrupting beneficial insect populations.

Products like AzaGuard®, which contains the botanical extract azadirachtin, can also be used either alone or with a biological material like BT NOW for controlling caterpillars. AzaGuard will also help to manage other pests such as aphids, whiteflies and thrips.

To learn more about which species of moths/caterpillars are most likely to be pests of your crops consult your regional crop production guides, reach out to your local extension agent, or ask a fellow farmer what they’ve seen over the years. 

To learn more about BT NOW please visit our website or give us a call.  Happy scouting!