Sugarbeet Root Maggot

family: anthomyiidae
species: tetanops myopaeformis
common names: sugarbeet root maggot
antennae characters: aristate
hosts: sugar beet,
notes:

Agriculture and Agri-Food Canada Insect Identification sheet No. 97 1986

Sugarbeet Root Maggot

Tetanops myopaeformis (Roder)

The sugarbeet root maggot is native to North America and has caused considerable economic damage to sugar beets in Canada and the western United States.

Injury:

On hatching, the maggot begins to feed on the small roots by rasping or cutting the tissues and lapping or sucking the released juices. If the beets are small when attacked or if the number of maggots is large, the taproot may be severed and the plant may die. Plants that survive a severe attack usually produce small and stubby roots with a low sugar content.

Life History:

The adult is a fly about 5.5-6 mm long with a glossy black body and smoky patches on the coastal margins of otherwise clear wings. The female has a long and distinct ovipositor The adults are very active from early June to early July mating and laying eggs shortly after they emerge from the soil. Calm warm weather at midday seems conducive to these activities. The female lays eggs singly or in clusters of up to 40, just below the soil surface in crevices near the seedling beet. The eggs are glossy, pearl white, slightly curved, pointed at one end and rounded at the other. They are about 1 mm long and 0.25 mm wide.The eggs usually hatch within 3 days and the larvae, or maggots, move down through the soil to feed on the taproot. After feeding for approximately 2 months the mature maggots begin to burrow their way deep into the soil (up to 45 cm) where they overwinter.

The mature maggot is yellow-white, about 10-12 mm long, with very distinct inter segmental constrictions along its length. It tapers toward the head, which is the smaller end. The larger caudal end has two light-brown plates attached which are pointed and curve out away from the body. In spring, as soil temperatures increase, the larva moves upward to within 2.5-7.5cm of the soil surface, where it pupates. The light-brown pupa has the same distinct inter segmental constrictions as the larva,is symmetrical with rounded ends and approximately 8 mm long. The adult emerges in June and early July.

Pest Management:

Seed beets in early spring when danger of frost is over, to obtain a robust stand. Seeding the new crop as far as possible from the previous year's may reduce the risk of infestation. Consult your provincial Department of Agriculture or sugar beet fieldman for specific control recommendations.