II.2. SQUASHES, PUMPKINS, ZUCCHINIS, GOURDS (CURCURBITA SPECIES) – 127
Coleoptera
Beetle species most commonly found on Cucurbita species include: the stripped
cucumber beetle, Diabrotica undecipunctata, and the spotted cucumber beetle,
Acalymma vittata. Beetles such as the palestriped flea beetle, Systena blanda, can also
attack plants of the Cucurbita.
Cucumber beetles (the stripped cucumber beetle, Diabrotica undecipunctata, and the
spotted cucumber beetle, Acalymma vittata) are common pests on various members of the
Cucurbitaceae. The name stems from the tendency of these beetles to be found on
cucurbits. These coleopterans are among the first insects to attack cucurbits as the plants
emerge. The spotted cucumber beetle is about 0.25 inches long, yellow to
greenish-yellow with 12 black spots on its back and a black head. They overwinter in the
adult stage near plants and in debris. Some migrate south and have been known to travel
500 miles in 3-4 days. The larvae are yellowish-white with a brown head and a brownish
patch on top of the last body segment. The larvae feed on plant roots. When there is
ample moisture, they will feed on the flesh of the fruit, especially fruits lying on the soil
surface. Whereas larvae are root feeders, adults are primarily pollen feeders and do not
damage the leaves of cucurbits to a significant extent (Krysan and Smith, 1987; Eben and
Barbercheck, 1996; Gámez-Virués and Eben, 2005). The striped cucumber beetle is pale
white-yellow to orange with a black head. Its wings have three black stripes running their
entire length. Other than immediate stand loss, and damage to leaves, stems, blossoms
and fruit, damage is incurred from the beetles’ ability to carry the pathogen
Erwinia tracheiphila, which is carried in the insects’ body and transmitted to the plant as
the beetles feed (OMAFRA, 2011).
The palestriped flea beetle (Systena blanda) is a general feeder attacking a multitude
of plants. Larvae can be found feeding on roots. Adults attack the foliage of plants
leaving small round holes.
The squash-ladybird (Epilachna borealis) is a black-spotted, yellow hemispherical
species of wide geographical distribution. The adult beetles hibernate and lay their eggs
on leaves in the spring. The yellow, spiny larvae chew circular holes in the leaves.
A closely related species is Epilachna varvestis, the Mexican bean beetle. The Mexican
bean beetle resembles the ladybird; it is coppery coloured with 16 black dots in 3 rows
down its back. Its larvae are orange or yellow, humped-backed and fuzzy. Both feed on
the lower surface of leaves, skeletonise the leaf.
Lepidoptera
The term “cutworm” applies to the larvae of various moth species in the Noctuidae
family. Cutworms are general feeders and attack a wide range of plants, including the
cucurbits. These cucurbit pests include the black cutworm (Agrotis ipsilon), the granulate
cutworm (Feltia subterranea) and the spotted cutworm (Amathes c-nigrum).
These lepidopterans may injure many types of vegetables and sometimes cereals.
Larvae hide under clods or in tracks of the soil by day and feed at night, cutting young
plants near the ground or feeding on the foliage. They cause greatest damage to seedlings
and newly set plants, resulting in stand loss. Cutworms overwinter as larvae or pupae,
depending on the species.
“Melonworm” and “pickleworm” are the common names of the larvae of two moth
species in the family Pyralidae, with the name melonworm applying to the species
Diaphania hyalinata and the name pickleworm applying to the species