Integrated Pest Management Guide

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BLACKHEADED FIREWORM, Rhopobota naevana (Hübner)

Late July usually marks the end of the first flight of fireworm moths. Eggs laid by first-generation female moths hatch from late June through July, and second-generation larvae resume feeding on cranberry foliage. New tents and damage begin to appear along the edges of the beds in late June or early July. Depending on the timing of the larvae and fruit development, this second generation of larvae may burrow into the berries. Following pupation, moths of the second generation are present from late July through September. Most of the eggs laid by second-generation females enter diapause (a dormant, hibernation-like state for winter). However, a small percentage of eggs hatch to produce third-generation larvae that feed on fruit.

Control: During bloom, the application of insecticides that are toxic to bees is not recommended. The need for insecticide application may be reduced or eliminated by using 3M Sprayable Pheromone for Mating Disruption of Blackheaded Fireworm. Refer to the section "KEY PESTS: DORMANT TO PRE-BLOOM" for more information.

A tiny parasitic wasp, Trichogramma sibericum, is sometimes found in beds not treated with insecticides. These tiny wasps are well-adapted to parasitize fireworm eggs. Trichogramma are now available commercially and can be applied to cranberry fields during and after the second flight of fireworms to target eggs laid by females of the second generation. Trichogramma wasps reduce the number of fireworm larvae by consuming the contents of fireworm egg and emerging as Trichogramma adults the next spring. The current recommendation is to apply 800,000 Trichogramma per acre divided into two applications 7 - 10 days apart. This biological control agent is well suited as a companion technique with mating disruption since the wasps parasitize high levels of fireworm eggs in "hot spots", while mating disruption is most effective at low fireworm densities. Both techniques are best used with the advice of a pest management specialist.


Blackheaded fireworm larva	Blackheaded fireworm moth